by What was little more than a speck of light for the Hubble Space Telescope has been revealed as one of the oldest galaxies ever discovered – and the decision is owed to none other than Hubble’s younger sibling: the James Webb Space Telescope.
The International Cooperation James Webb Space Telescope “Glass” made detailed observations of the galaxy, called Gz9p3, which appears as it was just 510 million years after the Big Bang. That was during the relative youth of the universe, which is now 13.8 billion years old.
The team found that, like other early galaxies seen by the JWST, Gz9p3 is much larger and more mature than expected for a galaxy in the infant universe. During the ancient period in which it appears, it already appears to contain several billion stars.
When it comes to the cosmic puzzle of how early galaxies grew to be so massive so quickly Gz9p3 could be the real answer. Not only is it larger than expected, but it is about 10 times larger than other galaxies seen by JWST in similar eras of the universe’s history.
Related: The James Webb Space Telescope complicates the expanding universe paradox by checking Hubble’s work
“Just a few years ago, Gz9p3 appeared as a single point of light through the Hubble Space Telescope,” Kit Boyett, a team member and scientist at the University of Melbourne, wrote for the institute’s publication Pursuit. “But by using the JWST we could look at this object as it was 510 million years after the Big Bang, about 13 billion years ago.”
gz9p3 is amazing. Apart from its size and maturity, its shape also reveals clues to its creation.
Did a merger of early galaxies create Gz9p3?
Using the JWST and direct imaging, the team was able to determine that Gz9p3 has a complex shape with two bright patches that reveal its two dense nuclei. This suggests that Gz9p3 was likely formed when two early galaxies smashed together in the infant universe. This collision may have been ongoing at the time astronomers observed Gz9p3 with the JWST.
“The JWST imaging of the galaxy shows a morphology typically associated with two interacting galaxies. And the merger is not complete because we still see two components,” explained Boyett. “When two massive objects like this merge, they effectively throw away some of the matter in the process. So this discarded matter suggests that what we’ve observed is one of the longest mergers far that was ever seen.”
In addition to determining the age, mass and shape of this ancient galaxy, Boyett and his colleagues were able to probe deeper into Gz9p3 to examine the stellar population of these colliding galaxies. Because young stars are brighter than their older counterparts, they tend to dominate images of galaxies, especially those that are so far away that their light has traveled to Earth over billions of years.
“For example, a bright young population triggered by the galactic merger, less than a few million years old, outperforms an older population that is already over 100 million years old,” continued Boyett.
The Glass collaboration worked around this by taking spectroscopic observations of Gz9p3 and using direct imaging. Spectroscopy can be used to determine the elements that make up stars; Because young and old stars have different compositions, this allowed the researchers to separate the two categories in this early galaxy.
Older stars have worked their way through the supply of hydrogen in their cores, having already fused it into helium and then fusing this helium to create even heavier elements, which astronomers call “metals”. This means that older stars are richer in metals than younger stars, which are still dominated by hydrogen and some helium.
The study team used the JWST to detect specific features in the older star population Gz9p3. Those target elements included silicon, carbon and iron, the latter of which is the heaviest element stars can synthesize. This means that these stars, when they died in supernova explosions, would have enriched the early universe with metals. Much of this metal material would become the building blocks for the next generation of stars.
In addition, the team found that the population of old stars in Gz9p3 was much larger than previously suspected. This means that while astronomers are aware of this cycle of stellar life and death and the increasing metal enrichment of subsequent generations of stars, Gz9p3’s observations show that galaxies may be “chemically mature” faster than as previously suspected.
“These observations provide evidence for a rapid and efficient accretion of stars and metals immediately after the Big Bang, linked to ongoing galaxy mergers, showing that massive galaxies with several billion stars existed earlier than previously thought. looking forward to it,” Boyett wrote.
History of violence
Galaxies that sit isolated from their fellow galaxies form stars, but the process is slow and ends when that galaxy exhausts its reservoir of gas and dust, the materials that form stars.
In the case of galaxies that are close to each other, the star formation process can be accelerated and even revived after its termination. That is why when these galaxies are pulled together by each other’s gravity, they collide. The merger then causes an influx of fresh gas that begins a period of rapid star birth called a “starburst,” meaning that mergers provide a great way for galaxies to rapidly grow their stellar populations.
Most large galaxies in the universe have grown in this way; Our own galaxy, the Milky Way, reflects the merger history itself. For example, it involved cannibalizing smaller satellite galaxies that once orbited it. The Milky Way currently forms stars at a stunted rate, but this will change when it collides with our nearby galaxy, Andromeda, in about 4.5 billion years. This will cause an influx of gas that starts a fresh bout of starburst.
Thanks to Gz9p3’s observations, astronomers are getting the message that this channel for rapid mass accumulation and star birth was a bigger factor in the early universe than previously thought.
Related Stories:
— The James Webb Space Telescope takes in the star-forming region of the Triangulum Galaxy (images)
— The James Webb Space Telescope’s targets for next year include black holes, exomoons, dark energy – and more.
— The James Webb Space Telescope may have discovered some of the 1st stars
“The Gz9p3 observations show that galaxies were able to rapidly accumulate mass in the early universe through mergers, with higher star formation efficiencies than we expected,” explained Boyett. “This and other observations using the JWST are causing astrophysicists to adjust their modeling of the early years of the universe.
“Our cosmology is not necessarily wrong, but our understanding of how fast galaxies are formed probably is, because they are larger than we ever believed possible.”
The team’s research was published on March 7 in the journal Nature Astronomy.
